CVE-2026-70355: Microsoft SharePoint Server Elevation of Privilege Vulnerability
CVE-2026-70355 is an elevation of privilege vulnerability in Microsoft SharePoint Server, rated Important by Microsoft, with a CVSS 3.1 base score of 7.3 (High). An attacker can exploit it remotely over the network, with low privileges and only if a user takes an action. Microsoft has not reported exploitation in the wild and rates exploitation as more likely. The EPSS model estimates a 0.78% probability of exploitation activity in the next 30 days, higher than 56% of all scored vulnerabilities. Microsoft released the fix on 11 August 2026 in the August 2026 Patch Tuesday, delivered through 3 security updates (KB5002894, KB5002896, KB5002893). It affects 2 products in 1 product family (Microsoft Office).
Key facts
- CVE ID
- CVE-2026-70355
- Severity
- High CVSS 7.3
- Microsoft severity
- Important
- Impact
- Elevation of Privilege
- Exploited in the wild
- No
- Publicly disclosed
- No
- Exploitation likelihood
- More Likely
- Weakness
- CWE-79
- EPSS
- 0.78% (percentile 56%)
- CISA KEV
- Not listed
- Released
- Last updated
- Patch Tuesday
- August 2026 Patch Tuesday
- Product families
- Microsoft Office
CVSS score and vector
Microsoft scores CVE-2026-70355 at 7.3 (temporal 7.3) using CVSS 3.1. Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N
| Metric | Value |
|---|---|
| Attack vector | Network |
| Attack complexity | Low |
| Privileges required | Low |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality impact | High |
| Integrity impact | High |
| Availability impact | None |
Description
Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Office SharePoint allows an authorized attacker to elevate privileges over a network.
Frequently asked questions (Microsoft)
What privileges could be gained by an attacker who successfully exploited this vulnerability?
Successful exploitation could allow an attacker to run script in the security context of the affected SharePoint user and perform actions permitted to that user.
There are multiple update packages available for some of the affected software. Do I need to install all the updates listed in the Security Updates table for the software?
Yes. Customers should apply all updates offered for the software installed on their systems. If multiple updates apply, they can be installed in any order.
Affected products (2)
Microsoft Office
Security updates (3)
NIST NVD data
- NVD status
- Analyzed
- NVD CVSS
- 7.3 (HIGH)
- NVD weakness
- CWE-79
- Published to NVD
- NVD last modified
Affected configurations (CPE)
| Product | Vulnerable versions |
|---|---|
| sharepoint server | before 16.0.19725.20522 |
| sharepoint server 2019 | all listed versions |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-70355 (Vendor Advisory, Patch)
Acknowledgments
Revision history
| Version | Date | Description |
|---|---|---|
| 1.0 | Information published. |